Simple script to update your GoDaddy DNS server to the IP address of your current internet connection.
Add several entries to your crontab (crontab -e) for each A record you wish to update:
*/30 * * * * /script/godaddy_ddns.sh personal example.com >> /script/godaddy_ddns.log
*/30 * * * * /script/godaddy_ddns.sh myftp example.com >> /script/godaddy_ddns.log